An RFID (Radio Frequency IDentification) tag is sometimes also referred to as a wireless IC (Integrated Circuit) tag, and is used for various purposes. For example, the RFID tag may be used in a high-temperature environment. In a case in which the RFID tag is provided on a component or the like, for example, position information of the RFID tag may be read by a tag reader or the like that reads information stored in the RFID tag, in order to confirm a location of the component or the like. In addition, the tag reader or the like may read log information stored in the RFID tag, in order to confirm a log of use of the module or the like.
In a case in which the RFID tag is provided on a module that is exposed to a high-temperature environment, such as a module or the like arranged in a periphery of an engine, for example, heat insulating measures are preferably taken with respect to a semiconductor device within the RFID tag, because the semiconductor device has a relatively low heat resistance. When no heat insulating measures are taken with respect to the semiconductor device, a guaranteed life for retaining data in a semiconductor memory, for example, may become short, and an operation failure of a semiconductor circuit may occur. Hence, in general, the RFID tag that is used under the high-temperature environment is covered by a package or a heat insulating material, in order to suppress heat transfer to an inside of the RFID tag and delay a temperature rise inside the RFID tag to provide the heat resistance.
In order to improve the heat resistance of the RFID tag, the package or the heat insulating material may be made thick so that the heat transfer to the inside of the RFID tag is further suppressed. However, when the package or the heat insulating material is made thick, a volume of a package structure of the RFID tag becomes large, and as a result, a weight of the package structure increases.
An example of the IC tag is proposed in Japanese Laid-Open Patent Publication No. 2008-310387.
In a conventional package structure, such as a heat-resistant package structure for the RFID tag, it is difficult to improve the heat resistance while maintaining the volume of the package structure unchanged and without increasing the weight of the package structure. In other words, in the conventional package structure, it is difficult to simultaneously reduce the weight and improve the heat resistance, while maintaining the volume of the package structure unchanged.